Metallic test access

MTA provides a set of subscriber line tests both for narrowband and for broadband.

MTA is performed on a line-by-line basis using TL1 or AMS.

MTA is a partially integrated test facility:

• MTA relies on a non-integrated Remote Test Unit (RTU) that is connected to the ISAM or ISAM Voice.

• MTA requires MTA-capable appliques terminating the subscriber line.

MTA can be used to set the relays so that the RTU gets outward access to, for example, the narrowband physical line, the broadband physical line, or the full physical line. MTA also allows setting the relays so the RTU gets inward access to test, for example, the narrowband towards the LT board terminating the POTS or ISDN line, or the broadband towards the LT board terminating the DSL line.

Note that it is possible to test the narrowband of a line from two different places:

• the narrowband line can be tested outward from the Voice applique, in which case it is managed as a test of the POTS line.

Although the MTA technology applies in principle to POTS and ISDN, it must be noted that it is supported only for POTS.

• the narrowband line can be tested outward from the splitter board (DSL applique) that is associated with a DSL LT board, in which case it is managed as a test of the DSL line.

In this way the MTA technology is supported for POTS and for ISDN lines.

It is also possible to equip collocated expansion shelves with MTA-capable

appliques and to connect them to the host shelf with a cable, to support the same tests from the RTU connected to the host shelf.

Some tests can be executed during turn-up of a subscriber line, for example, the operator can test the line to verify whether it is suited to carry the promised xDSL service. After the service has been established, the operator can also perform a variety of tests during routine or diagnostic tests.

Testing using MTA can be either single-ended or dual-ended.

5 — Line testing features

Test access modes

The following test access modes are supported for each Test Access Port (TAP):

• Released mode: releases all test connections and frees all TAP resources.

• Loop around mode: characterizes the TAP so that its influence can be deducted from the parameters measured during the split access mode.

• Split access mode: provides a breaking connection that allows the test system testing outwards toward the line and testing inward towards the LT equipment.

Figure 5-2 shows the test access modes.

Figure 5-2 Test access modes

The two following access modes are partial implementations of the split-access mode and are called “limited test access”:

• Limited outward access mode: provides a breaking connection that allows testing outward toward the line. The Low Pass Filter (LPF) and the line to the Public Switched Telephone Network (PSTN) remain connected to the line. This limits the number of measurements that the test system is capable of.

• Undisturbed outward access mode: provides a breaking connection that allows testing outward toward the line. The LPF and the line to the PSTN are either not present or they have been removed from the line. This ensures that the

measurements are not disturbed by the presence of the LPF or the DC battery voltage that is put on the line.

Figure 5-3 shows the partial implementations of split-access mode.

Note — Only full MTA requires all the test access modes.

Split access

Equipment pair Facility pair

RTU

DSLAM Line

PSTN LPF

xTU-C LPF

Released Loop around

Facility pair

Equipment pair

Facility pair

Equipment pair RTU

DSLAM DSLAM

Line Line

PSTN PSTN

LPF

xTU-C xTU-C

RTU

5 — Line testing features

Figure 5-3 Partial implementations of split-access mode

MTA support in the 7302 ISAM

Full test access scenarios are supported, using the Metallic Test Access Unit (MTAU) function. The MTAU function is implemented using a test applique and LT appliques, which are present in the splitter shelf. Using this function, a test head or Remote Test Unit (RTU) can get metallic access to a line in the 7302 ISAM by way of a TAP, to perform the necessary tests.

MTA support in the 7330 ISAM FTTN

Full test access scenarios are supported in the 7330 ISAM FTTN. The expansion nodes (expansion shelf and REM/SEM) do not support MTA.

• The 7330 ISAM FTTN shelf supports MTA through an MTAU function implemented by the test access board (or NTIO board with MTA function), in conjunction with the multi-ADSL and POTS splitter appliques. All units must be present in their respective shelf for the MTAU function to operate. Using this MTAU function, a test head or RTU can use a single TAP on the test access board to get metallic access to any subscriber line connected to the 7330 ISAM FTTN.

• The 7330 ISAM FTTN shelf uses an RJ-45 MTA connector on the test access board as the TAP for the test in and test out signals between the testhead and the shelf.

• The 7330 ISAM FTTN shelf uses these boards to provide a relay-based matrix to connect the test in and test out signals with the backplane for connection to the appropriate applique installed in the shelf.

• The 7330 ISAM FTTN shelf supports MTA on the multi-ADSL and POTS splitter appliques. On-board relays are used to connect the test in and test out signals to the appropriate connected subscriber line.

RTU RTU

Limited outward access Undisturbed outward access

Facility pair Facility pair

Equipment pair Equipment pair

Line Line

LPF LPF

x-TU-C x-TU-C

PSTN PSTN

DSLAM DSLAM

Note 1 — The MTA test bus may be interconnected / daisy chained for up to 8 collocated FTTN host nodes using a maximum cable length of 10 m.

Note 2 — Since MTA is currently supported on host nodes only, the Test Operating System must insure that only one port in this daisy chain configuration is enabled at any one time

5 — Line testing features

Test Access Control

Test Access Control (TAC) is done with TL1 commands, which are sent using the TL1 agent of the 7302 ISAM or 7330 ISAM FTTN shelves in response to the test head.